Exhaust silencer for internal combustion engines



EXHAUST SILENCER FOR INTERNAL COMBUSTION` ENGINES Filed April 4, 1929 2Sheets-Sheet 2 g 76 75 77 d0 J/ INVETOR ler subdivides the gas streaminto a Patented Oct. 25, 1932 UNITED STATES .PATE-NT oFFics GIUSEPPENICOLICH, F NEW YORK, N. Y., ABBIGNOB OF FIFTEEN PEB CENT T0 FLORENCEHAMILTON AND 0F FIVE PEB CENT TO BEBTA CUTTI, BOTH OF NEW v uv 'n1 v .Laan, A1. a..

EXHAUST BILENCER FOB INTERNAL COHBUSTIQN ENGINES Application nled April4, 1929, Serial No. 858,357, and in Italy January 11, 1928.

This invention relates to devices for silencing the exhaust gases ofinternal combustion en rines and comprehends devices involvin ditlierentmodifications particularly ada te for silencing the exhaust gases ofaerop ane, automobile, motor-boat and the like engines.

The majority of prior devices adapted to reduce the noise of the exhaustof internal combustion engines only operate effectively under definiteconditions such as a predetermined velocity or pressure of the exhaustgases and with an exhaust gas volume which must remain practicallyconstant, but under all other conditions such devices are inefficientand ineffective-for the intended urpose of completel silencing the exlosions of the engine an build up a considerable back pressure whichimpairs the efiiciency of the engine.

It is the principal object of this invention to provide a silencer forinternal combustion engines of all kinds, which obviates theaforementioned objections to present devices, by being efiicient andeffective to reduce the noise of an internal combustion engine at allspeeds and under all conditions of gas velocity and volume withoutaffecting the operation of the engine in anv way. A further object is toprovide a evice which is simple and efficient for the purpose intended,and one which is liUht in weight, compact, fool-proof and not li ely toget out of order under the most severe operatin conditions.

These and other objects are o tained in a preferred embodiment of theinvention including a connection from the exhaust manifold of aninternal combustion engine to one or more circular chambers containingpropeller wheels adapted to be rotated at high speed by the kineticenergy of the exhaust gases, the exhaust ases being so directed as toimpin e upon t e tips of the blades of the rope 1ers whereby eachsucceeding blade of the consequently rapidly rotating propelgreat numberof parts which are further subdivided li y the deflection thereofthrough a disc placed parallel to the normal gas stream beforeexiausting into the atmosphere, this angular deflection being producedby the peculiar shape of the blades of the ropeller. For purposes ofsilencing the ex aust of an internal combustion engine whose exhaustgases are discharged therefrom at comparatively low s eed, one propellerchamber has been foun satisfactory, but for engines whose exhaust gasesare discharged at very high speeds 'and in which the range of exhaustgas speeds 'varies greatly, such as in an aeroplane engine, a pluralityof chambers is employed, t ese chambers being arranged and connected inseries, the as stream being divided in the first cham er of the seriesand a gert thereof deflected through the perforate plate into theatmosphere while the remainder of the gas stream, still travelling at hih velocity, is conducted to the succeeding c ambers of each series ofchambers for further subdivision and deflection into the atmospherethroa h the perforated plates individual to each c amber, in the mannerdescribed iii connection with the single or iirst chamber.

It has been found that for high speed engines such as aeroplane engines,a plurality of such sets of tandem chambers are necessary, for thereason that one chamber, even if made large enough, will not subdividethe gas sufficiently to procure the silencing action intended i. e., aplurality of small propellers in a plurality of chambers subdivide thegas stream into a greater number of parts for the same gas velocity witha consequent greater silencing action. In fact, the greater the volumeof gas and the eater the velocity thereof, the greater sieicing theaction procured by the device of this iiiveiition, so that aeroplaneengines, for example, are silenced more effectively at hi hest s eedswhen the greatest noise ordinari y resu ts.

For a better understanding of the invention, reference is made to theaccompanying drawings, in which Figure 1 illustrates in elevation apreferred embodiment of the exhaust silencer of this invention as it maybe ada ted for use in silencing the exhaust of aerop ane engines;

Fig. 2 is a longitudinal section thereof as seen along the line 2 2 ofFig. 8;

Fig. 3 is a plan view thereof as seen along the line 3--3 of Fig. 1;

Fig. 4 is a transverse section thereof as seen alor. the line 1f-4 ofFig. 1;

Fig. 5 1s a transverse section of the exhaust silencer of this inventionhaving one propeller chamber and particularly adapted for automobiles orother internal combustion engines whose exhaust gases are discharged ata comparatively low speed;

Fig. 6 is a transverse section thereof as seen along the line 6 6 ofFig. 5; and

Fig. 7 is a plan view shown in partial section of a similar silencerembodying this invention and provided with means for eliminating theharmful carbon monoxide gases contained in the exhaust gases of theengine.

In these drawings, numeral 10 designates the exhaust manifold of'anaeroplane engine, not shown, this exhaust manifold 10 being connected bya gas-tight flexible tube 11 to the intake funnel 12 of the exhaustsilencer 13 of this invention which is adapted to be mounted by means ofplate 14 to some portion of the aeroplane such as on the underside ofthe fuselage or the upper lane thereof. As shown in Fig. 1, the si encer13 is placed in the osition which it would occupy when mounted on thetop plane of an aeroplane, whereas if it were mounted on the undersideof the fuselage, for example, it would be turned upside down and securedto the fuselage by means of plate 14. An asbestos or other thermalnonconducting sheet 14 is interposed as a heat insulator between thesilencer proper and the mounting plate 14. A

As shown particularly in Fi s. 2 and 3, the funnel 12 1s fitted with aper orated cone 15, the perforations of which are preferablyofvaryingsizes. Becauseofthislargeconical surface, a greater number ofperforations are possible and the consequent subdivision of t e gasstream is increased without requiring any increase in the volume ofexhaust gases passlng throu h funnel 12. Funnel 12 1s connected as-tigtly to the easing 16 of the silencer, t is frame being perforated forcooling purposes and being torpedo-shaped to provide minimum airresistance and obtain a generally stream-line effect.

As shown particularly in Fig. 3, the exhaust gases emerging through theperforated cone 15 are divided mto two streams passing through passages17 and 17', these passages being formed in casing 16 by horizontalpartition 18 and vertical partition 19. Passage 17 dischargestangentially into circular chamber 20 formed by the circular sheet metalpartition 21, while pasage 17' discharges into circular chamber 20' alsoformed by partition 2l. Partitions 18 and 21 form with the casing 16 acooling chamber 22 in which air is circulated through the aforementionedperforations in casing 16 when the aeroplane moves through the air andas thc propeller of the aeroplanedefiects the air streams to the rearover the surfaces of the aeroplane and the attached silencer 13.

Chambers 2O and 20' are separated by a partition formed of a sheet metalcup 23 in which is placed a disc 24 of asbestos or other heat insulatingmaterial over which is plm-od l a sheet metal disc 25 secured inposition by the crimped edges of the cup 23, as shown particularly inFig.'3. Inserted through the partition 23, 24, 25 thus formed, is anoil-less journal 26 lubricated by graphite, which is unaffected by theheat of the exhaust gases, this graphite-lubricated journal beingremployed because, if oil were used, as a lubricant, this oil would soonburn out because of the hot gases surrounding the journal. Passingthrough journal 26 is a shaft 2T upon which, between collars 28, areournalled propellers 29 and 29' located within chambers 2O and 20',respectively. The free ends of the shaft 27 are journalled ingraphite-lubricated bushings 30 and 30'. mounted in perforated discs 31and 31' respectively, these discs being secured in the edges of conicalhoods 32 and 32', which are mounted gas-tightly over the open sides ofchambers 2O and 20', rcspectivel The b ades of propellers 29 and 29' arepreferably east integrally of Monel metal or other light and extremelystrong material, the ends of the blades being trussed by wires or rods33 so as to prevent distortion at high velocities and under hightemperature of the exhaust gases. The blades of the propeller-s 29 and29 are turned outwardly so as to deflect the gas which impingesthereupon in a direction at right angles to its normal flow throughpassages 17 and 17', whereby the gas is forced through perforated plates31 and 31 in the manner illustrated by the arrows in Fig. 3. As shown inFigs. 3 and 4, the blades of the propellers 29 and 29' are aperturedadjacent their axes to prevent resistance to rotation by eddying gaseswhich accumulate adjacent the propeller axes.

The passages 17 and 17 have orifices discharging tangentially intochambers 20 and 20', these orifices having a length as seen in Fig. 2 ofapproximately one-fifth of the circumference of these chambers 2O and20'` so that the exhaust gases impinffe with limited constriction uponthe tips of the blades of' propellers 29 and 29', which are accordinglyrotated in a counterclockwise direction, as seen in Fig. 2, and at highvelocity by the kinetic energy of the exhaust gases in proportion totheir speed. Because of the peculiar shape of the propeller blades, asthe blades pass the entrance orifices of passages 17 and 17', each bladecuts off a portion of the gas stream issuing therefrom and dcflectsthisl portion at right angles through perforated plates 31 and 31 toexhaust into hoods 32 an d 32 respectively. Hoods 32 and 32 arepreferably-conical in shape as shown, and dischar e into tubes 34 and34', these tubes be1n fitte with constrictinnr nozzles 35 and 35 ogenerally Venturi tube shape so that the velocity of the gas isincreased by c onstriction through these nozzles before being dischar edthrough the emergence :lots of these nozz es into the atmosphere. Hoods32 and 32 are removably secured in place by wing nuts 36, so thattheymay be readily removed for inspection of the pro ellers and theperforated plates secured to t e respective hoods.

All of the exhaust gases are not discharged through nozzles 35, but aportion thereof passes tangentially out of chambers 20 andv 20 in thesame general direction that they were introduced into the chambersthrough assages 17 and 17. These remaining exiiaust gases passtangentially'out of chambers 2O and 20 through respective angularpassages 37 and 37 formed by sheet metal walls or horizontal partitions39 and 40 as seen in Fig. 2, and vertical partition 41 shown in Fig. 3,these partitions forming with casing 16 air cooling chambers 42 and 43through which the outside air circulates freely through theaforementioned perforations in the wall of casing 16 as the aeroplanepasses through the air and as the aeroplane propeller blatt flows overthe silencer 13 as a whole. The gas stream may be considered as flowingcontinuously through passages 17 and 37 on one side and passages 1l and37 on the other side, the blades of the respective propellers 29 and 29rotated thereby, removing portions of the stream which are carried pastthe discharge passages 37 and 37 to be exhausted through plates 31 and31', respectively, while that portion of the gas stream which is notremoved by the blades of the propellers sweeping past discharge openings37 and 37 flows through the passages.

Passages 37 and 37 are arranged diagonally in casing 16 and dischargetangentially into the upper portions of chambers 44 and 44',respect1vely. these circular chambers being formed by the rear wall ofcasing 16 and the arcuate partition 45, which preferably forms part. ofpartition 40, as shown particularly in Fig. 2. Chambers 44 and 44 areseparated by a heat insulated partition 46 which corresponds topartition 23, 24, 25 described above, and contain the respectivepropellers 47 and 47, which correspond to propellers 29 and' 29respectively. In a similar way, the shaft 48, upon which the propellers47 and 47 are journalled, is journalled in graphite bushing 4!) securedin partition 46 and at its end in graphite bushings 50 and 50 secured inperforated plates 51 and 51 mounted in hoods 52 and 52 having exhaustnozzles 53 and 53 and' secured by wing nuts 54 over the open sides 0fchambers 44 and 44', respectively.

In operation on an aeroplane engine, the

exhaust silencer of this invention described above subdivides the gasstream emerging from the exhaust manifold 10 of the engine into aplurality of small streams by means of perforatedcone 15, this being thefirst stage of gas subdivision. The. gas stream is then divided byartition 19 into two streams flowing througi passages 17 and 17 toimpingo tangentially upon the blades of propellers 29 and 29 mountedwithin'chambers 20 and 20', respectively. The propellers 29 and 29 arerotated in a counter-clockwise direction as in Fig. 2 by the kineticenergy of the rapidly flowing gases and the gas stream is subdivided' bythe blades of these pro ellers durinj"A 'what may be termed the seconsubdivision stage. A portion of these two subdivided gas streams isdeflected at approximately right angles by the peculiarly shaped bladesof the propeller through the perforated' plates 31 and 31 during whatmight be called the third subdivision stage, whereby that portion of theexhaust gases is silenced and is discharged through nozzles 35 and 35into the atmosphere.,

The remaining exhaust gases, still flowing at high velocity. fiowthrough passages 37 and 3T to impinge tangentially upon the blades ofpropellers 47 and 47, respectively. The kinetic energy of the gas streamin turn rotates propellers 47 and 47 in a clockwise direction, that is,in a direction opposite to the direction of rot-ation of correspondingpropellers 29 and 29', respectively. These propellers act in the sameway as the aforementioned propellers, and subdivide the gas streamduring the fourth subdivision stage by action of the rapidly movingblades into a plurality of portions which are deflected lat orally bythe turned blades through perforated plates 51 and' 5l in the fifthsubdivision stage to be exhausted into the atmosphere through nozzles 53and 53 in the manner described. The silencing action in the secondseries of chambers 54 and 54 is the same as that described in connectionwith the first series of chambers 20 and 20', and the explosions of theengine are entirely silenced, especially at high crank-shaft speeds.Obviously. more than four chambers could be similarly connected inseries pairs if desired, and for purposes of silencing the exhaust ofan. aeroplane or other high speed engine, it has been found that aplurality of chambers is necessary, these chambers being fitted withrelatively small propellers whose peripheral speed is considerablygreater than a larger propeller operating in a larger chamber, with theresult that the tips of the blades of the smaller propeller procure agreater subdivision of thc gas stream than would be the case if a largepropeller, whose peripheral sneed is considerably less, were used. Tosubdivide the gases in inverse proportion to their velocity and volume,the perforations in disc 31 may be made smaller than those in disc 51.

In cases where it is sought to silence the exhaust of internalcombustion en ines whose exhaust gases Vtravel at a relative y low speedas com ared to the velocity of the exhaust fases o an aero lane engine,a sin le chamlier may be ein oyed in a device o the type illustrated inFigs. 5 to 7, inclusive. .eferring particularly to Figs. 5 and 6, acircular casing 55 forms a circular chamber 56, into which the exhaustgas stream discharges tuugentially through the tube 57 connected to theexhaust manifold of the internal combustion engine, not shown. Tube 57is fitted with a flap valve 58, which is normally maintained open b thegas stream flowing in the direction of t 1e arrow shown in Fig. 2, butis closed by back pressure to revent return flow of the gases centainein chamber 56 due to any cause. Secured to brackets 59 mounted on theinner surfaces of the housing 55 is a shaft 60 upon which is {'ournallcdthe propeller 61, tiis propeller ravine' opposite y turned blades so asto deflect tlie gases impingin on the center thereof in oiposite lateralirections. The propeller blades are also apertured at 62 toppreventresistance to the motion of the propeller by eddying gases which areliable to accumulate in )roximity to shaft 60. The gases are immediatelydeflected through perforated plates 63 and 63', from each of which arespaced the screens 64 and 64 respectively, which form with perforatedside plates 65 and 65 a pair of opposite chambers in which is mountedfilter consisting of a mass of metal or fibre wool 66 and 66',respectively. At the bottom of housing 55 is mounted a container 67forming a sump 68 which communicates through an opening with circularchamber 56. This sump is provided with a discharge opening normallyclosed by a valve 69 hinged to the lower surface of container 67, andnormally held closed by means of a Weight 70.

In operation, the gases emerging from the engine pass into tube 57through normally o en flap valve 58 and impinge upon the b ades ofpropeller 61 to cause rapid rotation thereof in proportion to thevelocity of the gas stream. The rotating blades passing the entranceorifice of tube 57 subdivided the gas stream into a plurality ofportions which are deflected laterally in opposite directions throughperforated plates 63 and 63', which further subdivide the gas stream andsilence the explosions of the engine. In assing through the masses ofwool 66 and 66 which are preferably saturated with some chemicalsolution to render harmless the carbon monoxide and other noxious gases,the gases are further subdivided and are discharged through perforatedside plates 65 and 65 into the atmosphere. The oils, water and otherliquids commonly contained in exhaust gases are precipitated uponperforated plates 63 and 63', and flow downwardly into sump 68 to becollected therein until the weight thereof counterbalances the weight60, whereb valve 69 is opened to automatically discliarge theaccumulated liquid.

In Fig. 7, another modification particularly adapted for internalcombustion engines whose exhaust ases are discharged at relatively lowspeeil, such as an automobile engine, is to the ex iaust manifold 72 ofthecngine, not shown. This tube 71 discharges into chamber 73, fittedwith the double deflecting propeller 74, which is mounted upon a hollowshaft 75, each end of which is journalled upon a pin 76, sc'nned to aperforated plate 77, only one of which is shown. This perforated plateis fitted with a handle 78 for ready removal thereof and cf thepropeller 74 for inspection` repair and the like. Perforated plate 77 isalso fitted with spacers 79 which properly locate it from a secondperforated plate 80, mounted in the hood 8l connected to the housingforming chamber 73. A similar set of perforated plates are mounted inthe opposite side of the device and a similar hood 8l is provided, thesehoods 81 and 8l being connected to the manifold 82, in the center ofwhich is mounted an open stack or chimney 83, to which the exhaust gasesfrom both sides` of the device are led. Within stack 83 is mounted anelectrical resistance coil 84, which is adapted to be connected by wireto the generator or battery of the automobile for the purpose of causingthe resistance coil to become incandescent and serve as an igniter.Discharging into stack 83 at igniter 84'are a pair of air tubes 86 and86 whose outer ends are placed in the air stream so as to supply air tosupport the combustion of the carbon monoxide gas mixed with the exhaustgases and thus render the gases harmless when they are discharged intothe atmosphere through stack 83.

It will be seen that the various modifications of the device of theexhaust silencer of this invention are efficient and effective forsilencing the explosions of an internal combastion engine with whichthey may be associated without affecting the efficiency or operationofthe engine by producing back pressure or resistance to the normaldischarge of the gases, the effectiveness of the apparatus beingproportional to the amount of noise produced by the engine, that is, thenoisier the exhaust, the more effective the silencing action of thedevice of this invention.

While several modifications of the invention have been illustrated anddescribed for rovided with the tube 7l connected lll llt

silencing the exhaust gases of internal comseveral modificationsdisclosed or by alterations and combinations thereof.

I claim:

1. In un internal combustion engineexhaust silencer the combination of acasing having a circular chamber, a multi-bladed wheel rotatably mountedin said chamber, the blades of said wheel being turned outwardly, atleast one stationary perforated member mounted on said chamber adjacentthe blades of said wheel and substantially parallel to the plane ofrotation thereof, a reducing discharge nozzle communicating with saidmem er and a tube leading from the exhaust pipe of the enginetangentially of said wheel into said chamber.

2. In an internal combustion engine exhaust silencer, the combination ofa circular casing, a substantially straight tube connected to theexhaust pipe of the engine and communicating tangentially with theinterior of said casing, a multi-bladed wheel rotatably mounted in saidcasing, the blades of said wheel extending substantially to said tube,at least one stationary perforated member mounted adjacent the blades ofsaid wheel and substantially parallel to the lane of rotation thereof,sald wheel being a apted to be rotated by the exhaust gas stream, todefleet the gas laterally through said member, and a Venturi dischargenozzle communicating with said member.

3. In an internal combustion engine exhaust silencer, the combination ofa circular casing, a substantially straight tube connected to theexhaust pipe of the en ine and communicating tangentially with t einterior of said casing, a multi-bladed wheel rotatably mounted in saidcasing, the blades 0f said wheel extending substantially7 to said tube,and a Venturi discharge nozz e communicating with the interior of saidcasing,.said wheel being adapted to be rotated by the exhaust gas streamto defiect the gas laterally through said nozzle.

4. In an internal combustion engine exhaust silencer, the combination ofa circular easing, a substantially straight tube connected to theexhaust pipe of the engine and communicating tan entially with theinterior of said casing, a muIti-bladed wheel rotatably mounted in saidcasinff, the blades of said wheel adapted to extend substantially tosaid tube, at least one stationary perforated memhcr mounted adjacentthe blades of said wheel and substantially arallel to the plane ofrotation thereof, an a reducing nozzle mounted over said member, saidWheel being adapted to he rotated by the exhaust gas stream to deflectthe gas laterally through said member and nozzle.

5. In an internal combustion engine exhaust silencer, the combination ofa casinv having a chamber, a multi-bladed whee mounted for rotarymovement therein, a passage leading from the exhaust pi of the enginetangentially into said cham er, at least one other chamber, amulti-bladed wheel mounted for rotary motion therein, a passagetanentiall interconnectin said chambers, an latera outlet ports oreachof said chambers.

6. In an internal combustion engine exhaust silencer, the combination ofa casing having a chamber, a multi-bladed whee mounted for rotarymovement therein, a passage leading from the exhaust pipe of the enginetangentially into said chamber, at least one other chamber, amulti-bladed wheel mounted for rotary motion therein, a passagetangentially interconnecting said chambers, lateral outlet ports foreach of said chambers, and perforated members in said outlet ports.

7. In an internal combustion engine exhaust silencer, the combination ofa casing having a chamber, a multi-bladed wheel mounted for rotarymovement therein, a passage leading from the exhaust pipe of the enginetangentially into said chamber, at least one other chamber, amulti-bladed wheel mounted for rotary motion therein, a passagetangentially interconnecting said chambers, lateral outlet ports foreach of said chambers, and discharge nozzles connected to said outletports.

8. In an internal combustion engine exhaust silencer, the combination ofa casing having a chamber, a multi-bladed wheel mounted for rot-arymovement therein, a passage leading from the exhaust pi e of the enginetangentially into said cham er, at least one other chamber, amulti-bladed Wheel mounted for rotary motion therein, a passagetangentially interconnecting said chambers, lateral outlet ports foreach of said chambers, perforated members in said outlet ports, anddischarge nozzles connected to said outlet ports.

9. In an internal combustion engine exhaust silencer, the combination ofa housing containing a series of chambers, a tube leading from theexhaust pipe of the engine tangentially into the first chamber, passagestangentially connecting the chambers in series, a multi-bladed wheel ineach of said chambers adapted to be rotated by the gas stream to de-{iect vas laterali out of the corresponding chamber, and a dischargenozzle for each of said chambers.

10. In an internal combustion en ine exhaust silencer, the combinationof a ousing containing a series of chambers, a pipe, leading from theexhaust pipe of the engine tangentially into the first chamber, amultibladed wheel mounted for rotary movement by the exhaust gas streamin each chamber, gas passages connecting said chambers in series anddischarging tangentially into each chamber, and a gas subdividing nozzlemounted substantially parallel to the plane of rotation of each of saidwheels, said wheels bein adapted to be rotated by the gas stream andeflect the gas laterally through said nozzles.

11. In an internal combuetion engine exhaust silencer, the combinationof a casing having a group ofv substantially circular chambers, a tubeconnected to the exhaust pipe of the engine and communicatingtangentially with each of said chambers, a multiladed wheel rotatablmounted in each of said chambers with tl'ie tips of the blades adaptedto project substantially to said tube, and nozzles arranged axiall ofsaid wheels, the blades of said wheels being turned to defleet a portionof the gases passing through said tube laterally through said nozzles.

12. In an internal combustion engine exhaust silencer, the combinationof a casing having a group of substantially circular chambers, tubemeans connected to the exhaust of the engine and communicatingtanentially with each of said chambers, a multi- Eladed wheel rotatablmounted in each of said chambers with tie tips of the blades adapted toproject substantiall to said tube means at least one perforatec memberarranged parallel to the plane of rotation of each of said wheels so asto be swept thereby, the blades of said wheels being turned to deflect aportion of the gases passing through said tube means laterally throughthe perforations in said member.

13. In an internal combustion engine exhaust silencer, the combinationof a casing having a series of substantially circular chambers, tubemeans connected to the exhaust pipe of the engine and communicatingtangentially with each of said chambers, a multi-bladed wheel rotatablymounted. in eachof said chambers with the tips of the blades adapted toproject substantially to said tube, at least one stationary perforatedmember arranged parallel to the p'ane of rotation of each of said wheelsso as to be swept thereby, and a nozzle mounted over each of saidmembers, the blades of said Wheels being turned to deflect a portion ofthe gases passing through said tu e laterally through said members andthe corresponding nozzles.

14. In an internal combustion engine exhaust silencer, the combinationof an elongated casing, partitions in said casing forming at least twocircular chambers, a tube leading from the exhaust pipe of the enginetangentially into the first chamber, a tube in said casing forming apassage between one side of the first chamber and the diagonallyopposite side of the second chamber, a multibladed Wheel mounted in eachchamber for rotation in opposite directions in response to the exhaustgas flow through said tubes, a stationary perforated plate mounted at aside of each chamber parallel to the plane of rotation of each wheel soas to be swept thereby, and a nozzle connected to each of said platesthe blades of each wheel being turned t.; deflect the exhaust gaseslaterally throu h the corresponding plate and nozzle.

15. n an internal combustion engine exhaust silencer, the combination ofa casing having a. chamber, a multi-bladed wheel mounted 'for rotarymovement therein, a passage leading from the exhaust pi e of the en ginetangentially into said cham er, at least one other chamber, amultibladed wheel mounted for rotary motion therein, a passagetargentially interconnecting said chambers, an Venturi discharge nozzlescommunicating with said chambers.

16. In an internal combustion engine exhaust silencer the combination ofa casing having a circular chamber, a multi-bladed wheel rotatablymounted in said chamber, the blades of said wheel being shaped todirect. the gases axially outwardly in both directions, at least onestationary perforated member mounted adjacent said chamber substantiallyparallel to the plane of rotation of said wheel, a reducing dischargenozzle communicating with said member and a tube leading from theexhaust pipe of the engine tangent-ially of said wheel into saidchamber.

In testimony whereof I alIix rn signature.

GIUSEPPE NI OLICH.

